refactor(protocol): extract an IBlockHash interface from TaikoL2 (#18045

)

Co-authored-by: dantaik <[email protected]>

packages/protocol/contract_layout.md

@@ -33,7 +33,7 @@
 | __paused        | uint8                       | 201  | 1      | 1     | contracts/L2/TaikoL2.sol:TaikoL2 |
 | lastUnpausedAt  | uint64                      | 201  | 2      | 8     | contracts/L2/TaikoL2.sol:TaikoL2 |
 | __gap           | uint256[49]                 | 202  | 0      | 1568  | contracts/L2/TaikoL2.sol:TaikoL2 |
-| l2Hashes        | mapping(uint256 => bytes32) | 251  | 0      | 32    | contracts/L2/TaikoL2.sol:TaikoL2 |
+| _blockhashes    | mapping(uint256 => bytes32) | 251  | 0      | 32    | contracts/L2/TaikoL2.sol:TaikoL2 |
 | publicInputHash | bytes32                     | 252  | 0      | 32    | contracts/L2/TaikoL2.sol:TaikoL2 |
 | parentGasExcess | uint64                      | 253  | 0      | 8     | contracts/L2/TaikoL2.sol:TaikoL2 |
 | lastSyncedBlock | uint64                      | 253  | 8      | 8     | contracts/L2/TaikoL2.sol:TaikoL2 |

packages/protocol/contracts/L2/IBlockHash.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.27;
+
+/// @title IBlockHash
+/// @notice Interface for retrieving block hashes.
+interface IBlockHash {
+    /// @notice Retrieves the block hash for a given block ID.
+    /// @param _blockId The ID of the block whose hash is being requested.
+    /// @return The block hash of the specified block ID, or 0 if no hash is found.
+    function getBlockHash(uint256 _blockId) external view returns (bytes32);
+}

packages/protocol/contracts/L2/TaikoL2.sol

@@ -11,6 +11,7 @@ import "../libs/LibAddress.sol";
 import "../signal/ISignalService.sol";
 import "./Lib1559Math.sol";
 import "./LibL2Config.sol";
+import "./IBlockHash.sol";
 
 /// @title TaikoL2
 /// @notice Taiko L2 is a smart contract that handles cross-layer message
@@ -19,7 +20,7 @@ import "./LibL2Config.sol";
 /// communication, manage EIP-1559 parameters for gas pricing, and store
 /// verified L1 block information.
 /// @custom:security-contact [email protected]
-contract TaikoL2 is EssentialContract {
+contract TaikoL2 is EssentialContract, IBlockHash {
     using LibAddress for address;
     using SafeERC20 for IERC20;
 
@@ -28,7 +29,7 @@ contract TaikoL2 is EssentialContract {
 
     /// @notice Mapping from L2 block numbers to their block hashes. All L2 block hashes will
     /// be saved in this mapping.
-    mapping(uint256 blockId => bytes32 blockHash) public l2Hashes;
+    mapping(uint256 blockId => bytes32 blockHash) private _blockhashes;
 
     /// @notice A hash to check the integrity of public inputs.
     /// @dev Slot 2.
@@ -95,7 +96,7 @@ contract TaikoL2 is EssentialContract {
         } else if (block.number == 1) {
             // This is the case in tests
             uint256 parentHeight = block.number - 1;
-            l2Hashes[parentHeight] = blockhash(parentHeight);
+            _blockhashes[parentHeight] = blockhash(parentHeight);
         } else {
             revert L2_TOO_LATE();
         }
@@ -150,7 +151,7 @@ contract TaikoL2 is EssentialContract {
 
         // Update state variables
         bytes32 parentHash = blockhash(parentId);
-        l2Hashes[parentId] = parentHash;
+        _blockhashes[parentId] = parentHash;
 
         publicInputHash = newPublicInputHash;
         parentGasExcess = newGasExcess;
@@ -223,7 +224,7 @@ contract TaikoL2 is EssentialContract {
 
         // Update state variables
         bytes32 parentHash = blockhash(parentId);
-        l2Hashes[parentId] = parentHash;
+        _blockhashes[parentId] = parentHash;
         parentTimestamp = uint64(block.timestamp);
 
         emit Anchored(parentHash, parentGasExcess);
@@ -276,14 +277,11 @@ contract TaikoL2 is EssentialContract {
         );
     }
 
-    /// @notice Retrieves the block hash for the given L2 block number.
-    /// @param _blockId The L2 block number to retrieve the block hash for.
-    /// @return The block hash for the specified L2 block id, or zero if the
-    /// block id is greater than or equal to the current block number.
-    function getBlockHash(uint64 _blockId) public view returns (bytes32) {
+    /// @inheritdoc IBlockHash
+    function getBlockHash(uint256 _blockId) public view returns (bytes32) {
         if (_blockId >= block.number) return 0;
         if (_blockId + 256 >= block.number) return blockhash(_blockId);
-        return l2Hashes[_blockId];
+        return _blockhashes[_blockId];
     }
 
     /// @notice Returns EIP1559 related configurations.

packages/protocol/contracts/mainnet/addrcache/AddressCache.sol

@@ -14,7 +14,7 @@ abstract contract AddressCache {
     function getAddress(
         uint64 _chainId,
         bytes32 _name,
-        function (uint64, bytes32) view  returns  (address) _fallbackFunc
+        function (uint64, bytes32) view returns (address) _fallbackFunc
     )
         internal
         view